This invention relates to a loading system for a material processing machine and more particularly to a system for transferring granular plastic materials into processing machines such as injection molding machines, extruders, blow molding machines and material dryers.
Machines for loading granular plastic materials into injection molding machines and the like have been available for a considerable period of time. Such machines normally include a large hopper assembly placed on top of injection molding machines and the like, making them very difficult to maintain and service.
In addition to the hopper, means are required for loading the hopper, normally an electrically driven vacuum motor. A number of problems have become manifest in the use of such machines. Typically the vacuum motor is very noisy, consumes considerable electricity and is dirty in that it blows fines of the material into the atmosphere. Such motors also require brushes that frequently wear out and have to be replaced. Frequently the machines currently in use also require expensive filter systems that have to be cleaned and replaced often. It is not unknown for such systems to become partially or entirely plugged, making it necessary to clean them out. They also have to be cleaned out after each run of a particular material to keep contamination to a minimum. Where such systems are on top of large hoppers on top of injection molding machines and the like, it becomes necessary for someone to climb up on the machine to effect the cleaning or maintenance. Sometimes machine components are broken, materials are spilled and wasted, or people are injured in falls in the course of effecting such cleaning because of the inaccessibility of such systems. It is, therefore, an object of the present invention to provide a loading system in which the loading process is considerably simplified and in which components for cleaning are readily accessible and easily handled from the floor.
Another area in which prior art machines appear to be unsatisfactory is that the various parts are not easily disassembled for cleaning. It is an object of the present invention to provide a material loading system in which the components are quickly and easily disassembled for cleaning by means of slip fit joints with O-ring seals.
Because of the fact that metal fragments and components sometimes find their way into the material it is known to provide a magnetic field somewhere in the system to trap such fragments and components. Disassembly to remove such metal fragments and components has generally involved a considerable expenditure of time. It is another object of the present invention to provide a material loading system including magnetic means in which the arrangement for removing such metal fragments and components is substantially facilitated.
Where there is an air driven system for transferring the granulated materials to the hopper from sources such as bags or barrels, it is frequently found that the conduit from the source to the hopper becomes plugged with material, frequently from packing and caking of the fines and/or chunks of material in the supply. It is therefore a further object of the present invention to provide an improved air driving system which is much less susceptible to such plugging.
In some applications it is desired to supply to the injection molding machine or the like, a mixture of two different kinds of such granular materials such as virgin plastic and regrind plastic. The usual system for accomplishing this mixture will load the virgin plastic for a few seconds and then load the regrind plastic for a few seconds. This builds up stratified layers of the separate materials in the hopper which causes process conditions to change from part to part and sometimes within the same part. As a result, the quality of the parts produced will vary, sometimes to an unacceptable degree. It is, therefore, a further object of the present invention to produce a material loading system in which a plurality of different granular materials can be supplied and blended together before being supplied to the associated machine.
Other objects and advantages will become apparent from consideration of the following specification taken in combination with the accompanying drawings.